New proposed methodology for specific heat capacity determination of materials for thermal energy storage (TES) by DSC

Abstract

This study presents a methodology to determine the specific heat capacity (Cp) of materials for thermal energy storage (TES) by DSC. These materials have great energy storage capacities, and due to that, important heat flow fluctuations can be observed for each temperature differential, taking more time to reach a desired temperature gradient. Three different DSC methods are considered to be applied in the methodology, and are explained and compared in this study in order to select the most proper one for Cp determination. To perform this study, the Cp of three materials commonly used in sensible TES systems, slate, water, and potassium nitrate (KNO3), is determined. Excellent results with errors lower than 3% are obtained when using the proposed methodology with the areas method. Worse results are obtained with both dynamic and isostep methods, with errors up to 6% and 16% respectively, as a consequence of sensitivity problems during the measurements.

The work is partially funded by the Spanish government (ENE2015-64117-C5-1-R (MINECO/FEDER)). The authors would like to thank the Catalan Government for the quality accreditation given to their research groups GREA (2014 SGR 123) and research group DIOPMA (2014 SGR 1543). The research leading to these results has received funding from the European Union's Seventh Framework Programme (FP7/2007-2013) under grant agreement n° PIRSES-GA-2013-610692 (INNOSTORAGE) and from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 657466 (INPATH-TES). Dr. Camila Barreneche would like to thank Ministerio de Economia y Competitividad de España for Grant Juan de la Cierva, FJCI-2014-22886.